No credit in 3 weeks

Hi recently purchased a pair of indoor boots from a adidas on line I made my choice as per the specifications of the boot as advertised on the site . The boots did not work as specified and I returned . I returned the boots 3 weeks ago yet I have not recieved my credit . It's totally unacceptable especially considering I have purchase just about 3k s worth from the adidas site since early January . Why does adidas feel is acceptable for a consumer to have to wait such a prolonged period of time to return goods and recieve credit when the consumer pays in an instant to get thier order . It's Rediculous